#include<iostream>
using namespace std;
class Sum
{
public:
    Sum()
    {
        _sum += _i;
        _i++;
    }
    static int getsum()
    {
        return _sum;
    }
private:
    static int _i;
    static int _sum;
};
int Sum::_i = 1;
int Sum::_sum = 0;
class Solution {
public:
    int Sum_Solution(int n)
    {
        Sum num[n];
        return Sum::getsum();
    }
};